Microtubules are hollow polymers made up of tubulin subunits. Neurons, like other eukaryotic cells, contain a pool of free tubulin subunits and a pool of the microtubule polymers. These two pools dynamically exchange with one another such that microtubules undergo bouts of assembly and disassembly.n neurons, microtubules are also nucleated at the centrosome (located in the cell body of the neuron), but the microtubules are then severed from the centrosome so that they can be deployed into axons and dendrites.
If the parent makes this election, the child does not have to file a return. Earned and Unearned Income. If a child has both earned and unearned income, he or she must file a return (2016 and 2015) if: unearned income was over $1,050; earned income was over $6,300, or
For the 2016 tax year (filed in 2017), single filers under the age of 65 who earn more than $10,350 and singles over 65 with more than $11,900 in earnings had to file a tax return. Head of household filers under 65 making more than $13,350 and those older than 65 with head of household status plus more than $14,900 in taxable income were also required to file.